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- Derleme MakaleAçık Erişim2026Scopus SJRQ1Quaternary palaeoenvironmental archives of the Indian subcontinent and their imprint on herpetofaunal biogeography: A multi-proxy synthesis
Kurnaz, Muammer
This review presents the first integrated proxy, mechanism and biotic-response framework for the Indian Quaternary, linking the Subcontinent's dense network of palaeoenvironmental archives to the biogeographic trajectory of its endemic herpetofauna. Speleothem δ18O records, Arabian Sea and Bay of Bengal sediment cores, Karewa and peninsular lake sequences, Siwalik and Narmada alluvium, and Kurnool cave deposits together document Indian Summer Monsoon (ISM) variability on orbital, millennial, centennial and historical timescales (the historical band here denoting the past ∼2000 years, resolved by dated speleothem and documentary records). Against this proxy backbone, the fossil and molecular phylogeographic record of Indian amphibians and reptiles is evaluated as a biogenic assemblage here, the body of biological evidence (fossils, subfossils and the phylogeographic signatures of living taxa) that, like pollen or foraminifera, records past environmental conditions that complements geological and climatological archives. Three patterns emerge. At orbital scale, ISM variability aligns with Plio–Pleistocene diversification slowdowns in Western Ghats ranoids and with the Late Pliocene lineage divergence of the Himalayan toad Duttaphrynus himalayanus across the Thakkhola basin. Abrupt Holocene excursions, including the 8.2 ka and 4.2 ka events, are resolved at high precision in speleothem and marine archives but remain untested against coalescent demographic inference in Indian herpetofauna. Late Pleistocene aridity, most severe at the Last Glacial Maximum, coincides with community-level impoverishment in peninsular cave faunas at Kurnool, although the available evidence establishes co-occurrence rather than a demonstrated causal role for aridity relative to co-varying thermal and vegetation change. Three proxy-calibrated research priorities follow: microvertebrate taphonomy in Narmada and Karewa sequences, population genomics tied to speleothem chronology, and species-distribution hindcasting to the LGM, mid-Holocene and 4.2 ka intervals. The synthesis contributes to a biogenic assessment of Quaternary-to-Recent climate impacts on life on the Indian Subcontinent, aligned with UN Sustainable Development Goals 13 (Climate Action) and 15 (Life on Land), and supports future projections of amphibian and reptile response to ongoing change.
- MakaleAçık Erişim2021Scopus SJRQ1Geochemistry and Pb isotopic proof for sources of heavy metal(loid)s in Late Cretaceous sandstones from Eastern Pontides (NE Turkey)
Saydam Eker, Çiğdem
Upper Cretaceous sedimentary rocks are widely exposed around Trabzon, Giresun and Gümüşhane in the eastern Pontides. The sedimentary rocks are mainly composed of sandstones and marls, and the thicknesses of these rocks range from 170 to 400 m. This paper focused on Late Cretaceous sandstones of Trabzon, Giresun and Gümüşhane regions to identify the concentrations, sources, deposition environment and conditions of certain heavy metal(loid)s (Zn, Pb, Cu, Ni, As, Co, Mo and V). Enrichment factor (EF), geo-accumulation index (Igeo), Pollution index (Pi), Pollution load index (Pln), Pb isotope and multivariate statistical analysis were performed to elucidate the pollution levels and sources. In general, the evaluation indices exhibited that the sandstones were moderately polluted by As in the Trabzon area, and strongly polluted by Ni and As, moderately polluted by Co and V in the Giresun and Gümüşhane areas. The results of multivariate statistical analyses indicated that As and partly Pb might be originated from anthropogenic sources, whereas other metals were derived from geogenic origin. Lead isotopic analysis demonstrated two characterized signatures of the pollution sources in the sandstones, one related to geogenic origin and the other to coal, gasoline and pesticides. The sandstones were deposited in transition—marine environment under oxic—weak oxic conditions and paleoclimatic conditions ranged from arid to moist during Late Cretaceous period.
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